Numerous processes are within the purview of those skilled in the art for the preparation of toners. Emulsion aggregation (EA) is one such method. Emulsion aggregation toners may be used in forming print and/or electrophotographic images. Emulsion aggregation techniques may involve the formation of a polymer emulsion by heating a monomer and undertaking a batch or semi-continuous emulsion polymerization, as disclosed in, for example, U.S. Pat. No. 5,853,943, the disclosure of which is hereby incorporated by reference in its entirety. Emulsion aggregation/coalescing processes for the preparation of toners are illustrated in a number of patents, such as U.S. Pat. Nos. 5,290,654, 5,278,020, 5,308,734, 5,344,738, 6,593,049, 6,743,559, 6,756,176, 6,830,860, 7,029,817, and 7,329,476, and U.S. Patent Application Publication Nos. 2006/0216626, 2008/0107989, 2008/0107990, 2008/0236446, and 2009/0047593. The disclosures of each of the foregoing patents are hereby incorporated by reference in their entirety.
Polyester emulsion aggregation (EA) ultra low melt (ULM) toners have been prepared utilizing amorphous and crystalline polyester resins as illustrated, for example, in U.S. Patent Application Publication No. 2008/0153027, the disclosure of which is hereby incorporated by reference in its entirety.
EA processes often use an aggregating agent, such as aluminum sulfate, for toner particle aggregation and for promoting crosslinking within the particle to reach a desired gloss level. However, the crosslinking agent may promote particle to particle sticking during coalescence, which could lead to a broad particle size distribution. Once the desired particle size is reached, a chelating agent, such as ethylene diamine tetraacetic acid (EDTA) is introduced to remove the extra aluminum after aggregation which helps prevent toner growth when the temperature is increased for coalescence. However, the addition of EDTA may prevent desired gloss modification from taking place. In addition, if the amount of EDTA utilized in the EA process is reduced, poor geometric size distribution (GSD) is obtained.
For many EA toners, there is a trade-off between obtaining desirable gloss and Minimum Fix (or Fusing) Temperature (MFT) characteristics. For example, many EA toners have high gloss and low melt properties. However, for applications where a lower gloss is desired, difficulties may arise in forming a toner having a lower gloss which still exhibits ultra low melt properties.
Improved toners and methods for their production thus remain desirable.